# Rename Multiple Files


You can rename a file using the `mv` command:

```command
mv file.txt newname.txt
```

If you need to mass-rename files, you can do so with a `for` loop in Bash.

For example, to rename all files in the current directory with the `.txt` extension to have the `.md` extension instead, execute the following command:

```command
for file in ./*.txt; do mv -v "${file}" "${file%.*}.md"; done
```

Within the `mv` command, you use some variables and shell substitution:

- `${file}` is the variable that refers to the current file name. The `file` variable is declared in the `for` loop.
- `%` indicates that you want to remove a suffix pattern from the end of the variable's value.
- `.*` is the pattern that matches the dot (`.`) followed by any characters (`*`), which represents the file extension in this case.
- `${file%.*}` removes the `.txt` extension from the file name.
- `"${file%.*}.md"` removes the .txt extension and appends `.md`, creating the resulting file name.

Using the `mv` command with the `-v` flag gives you a detailed output.

Running the command gives the following output:

```output
renamed './chapter1.txt' -> './chapter1.md'
renamed './chapter2.txt' -> './chapter2.md'
renamed './chapter3.txt' -> './chapter3.md'
renamed './chapter4.txt' -> './chapter4.md'
```

This is a fast and effective way to rename files.